Radon Overview
Radon Measurement
Learning Outcomes
Upon completion of this module you will
be able to:




Recall the certifying organizations for radon
testing devices and professionals
Identify “closed house conditions”
Determine the advantages of a long
term test
Recognize the types of radon tests typically
used in real estate transactions
Learning Outcomes
Upon completion of this module you will
be able to:


Recall where should the test be placed when
testing a room
Examine what duplicates and spikes measure
U.S. Exposure to Radiation
Internal
Other
Nuclear Medicine
Consumer Products
Terrestrial
Radon
54%
Cosmic
Medical X-Rays
Radon Measurement
Short and long-term testing devices
help determine the need for, and
effectiveness of radon mitigation
Radon Measurement
Closed house conditions for all short-term tests:
 All exterior doors and windows closed, except
for normal entry and exit
 Internal-external air exchange
systems off:
 Total internal recycle is allowed
 Combustion or make-up air must
not be closed

Permanent radon mitigation
systems remain on
How Long Will the Test Last?
Short-term test
Long-term test
2 to 90 days
Advantage
 Provides quick answer
Disadvantage
 Does not account for
radon variations from
day-to-day or seasonto-season
Used for most real estate
transactions
91 to 365 days
Advantage
Provides more information
about year-round average
radon level
Disadvantages
Takes longer to get results
Residents forget test is
running
Standards for Measurement Professionals and Devices

Testing may be conducted by professionals
certified by one of the following:
If you decide to do the testing
yourself, make sure the device
is approved by these
organizations
Types of Devices
Passive devices
 Do not require
power (electricity
or batteries) to
operate
 Less expensive
 Used in most real
estate transactions
Active devices
 Require power
to operate
 More expensive
 Require calibration
 Also used in real
estate transactions
General Testing: Passive Devices
If the first test result is 4pCi/L or more but under 10
pCi/L, conduct another short-term or long-term test
With another short-term test,
average the results of the first
and follow-up tests
With a long-term test,
use the long-term results
If the average is If the average
under 4 pCi/L, is 4 pCi/L or
test again in the
more,
future
mitigate
If the result is If the result is
under 4 pCi/L,
4 pCi/L or
test again in
more,
the future
mitigate
General Testing: Passive Devices
If the first short term test result is 10 pCi/L or
more:
 Conduct a follow-up short-term test
to confirm the reliability of the first test.
 The second result should not be more or
less than two times the first result.
 If it meets this requirement, mitigate.
 If it does not, retest.
General Testing: Active Devices
 Use any NEHA- or
NRSB-listed
continuous monitor
 Use a monitor that
integrates and
records at least
every hour
General Testing: Continuous Monitor
If the result is:
If the result is:
0–under
4 pCi/L
4 pCi/L or
more
Recommend
future retesting
Recommend
mitigation
Weather Conditions


Check local news stations for weather forecast
Do not test:
During extreme weather
 When extreme weather is predicted within 48 hours

Choose the Level to Test

If the home is not
being sold, test at
lowest level where
people actually live,
for example:
 Owners use unfinished
basement only for
storage
 Test on the main floor
If the home is being sold,
test at lowest level where
people could live without
renovating the area
 Buyers should discuss
and agree on placement,
for example:

 Buyers intend to use finished
basement as bedroom for
teenage son
 Test in basement
Consider Foundation Types

If a home has more
than one type of
foundation, test in
or above each area
Examples:
 If a home has a basement
that is or could be a living
space, test in the basement
 If a home has a crawl space,
test in the room above the
crawl space
 If a home has a room with
a cement floor, test in
that room
Choose the Room to Test
Select a room that is
used or will be used
regularly, for example:





Bedroom
Living room
Family room
Den
Playroom
Why?
These are rooms
where people
usually spend a
lot time
Rooms to Avoid

Kitchen
 Usually has exhaust fan
 Airborne particles may
affect measurement


 Dryer exhausts air
 High humidity

Bathroom
 People spend relatively
little time there
 High humidity may affect
some devices
Laundry room
Hallway
 People usually spend little
time there

Closet
 People usually spend little
time there

Crawl space
 People usually spend little
time there
Choosing the Location Within the Room
Place the device:
 Where it will not be disturbed
 More than one foot from exterior walls that have
no windows or other potential openings
 More than three feet from windows, doors, or
other potential openings in the exterior wall
 More than 4 inches from
other objects
 More than 20 inches from the
floor: “the Breathing Zone”
Precision

Are measurements repeatable or consistent when
an identical item is measured several times?

Measurements are precise (close together) but not
accurate (not near bull’s eye)
Accuracy

Are measurements close to the correct or true
value?

Measurements are accurate (in bull’s eye) but
not precise (close together)
Precise and Accurate
Precise
 Measurements are close together
Accurate
 Measurements are in bull’s eye
Tests for Passive Devices

Duplicates
 Measure precision

Spikes
 Measure accuracy

Blanks
 Measure bias (how
far measurements
are from accurate)
Active Devices


Calibrate at least once a year (or as
manufacturer suggests)
Check device manual or ask manufacturer
for a referral to a calibration lab
Summary
In this module we have discussed:




The certifying organizations for radon
testing devices and professionals
“Closed house conditions”
The advantages of a long-term test
The types of radon tests typically used in
real estate transactions
Summary
In this module we have discussed:


Where a radon test should be placed when
testing a room
What duplicates and spikes measure